1. Field of the Invention
The present invention relates to a light-emitting device including a p-insulator or a Si-n nanojunction region.
2. Description of the Related Art
Carbon nanotubes (CNTs), discovered by Iijima in S. Ijima Nature 354 56 (1991), as a by-product of the fullerene soot, are carbon hollow cylindrical-shaped molecules that, having a diameter of few nanometers and a length ranging in the micron scale, can be considered as molecular nanowires.
Their properties are determined by the number of graphene sheets (walls) forming a nanotube and by the fashion their atoms arrange in a wall. In particular, with respect to the number of graphene-sheets forming a nanotube, carbon nanotube basically occur in two distinguished types: MWNTs (Multi Walled NanoTubes) and SWNTs (Single Walled NanoTubes). Whereas, SWNTs are further characterized by the arrangement of hexagons, described by the chiral vector C, forming the honeycomb structure of the wrapped graphene sheet, with respect to the axis of the tube.
SWNTs have emerged in the field of molecular electronics because of their unique properties that allow for the manufacturing of devices such as FETs (field effect transistors) and SETs (single electron transistors). See in this respect the prior works by: S. J. Tans, A. R. M. Verschueren and C. Dekker Nature 393 49 (1998); R. Martel, T. Schmidt, H. Shea, T. Hertel and Ph. Avouris Appl. Phys. Lett. 73 2447 (1998); and S. J. Tans, M. H. Devoret, H. Dai, A. Thess, R. E. Smalley, L. J. Geerligs and C. Dekker Nature 386 474 (1997).
As a matter of fact, with respect to the conduction properties, SWNTs can be either semiconducting or metallic nanotubes, depending on the ‘wrapping’ of the graphene sheet (i.e., on their chiral vector). See in this respect: H. W. Ch. Postma, T. Teepen, Z. Yao, M. Grifoni and C. Dekker Science 293 76 (2001); M. Bockrath, D. H. Cobden, P. L. McEuen, N. G. Chopra, A. Z. A. Thess and R. E. Smalley Science 275 1922 (1997); A. Thess, R. Lee, P. Nikolaev, H. Dai, P. Petit, J. Robert, C. Xu, H. Lee, S. G. Kim, D. T. Colbert, G. Scuseria, D. Tomanek, J. E. Fischer and R. E. Smalley Science 273 483 (1996).
On the other hand, the recent finding of light emission or fluorescence in the near IR region from semiconducting SWNTs and FETs based on SWNTs increases and spreads the interest about the optical properties of these materials.
Because of the potential applications that would result from the exploitation of the optoelectronic properties of SWNTs (i.e., the possibility of building new devices), it is worthwhile to study the interaction of carbon nanotubes with radiation, especially in the near IR region that is of major interest in the field of telecommunication. Article of some interest are the following: M. J. O'Connell, S. M. Bachilo, C. B. Huffman, V. C. Moore, 1 M. S. Strano, E. H. Haroz, K. L. Rialon, P. J. Boul, W. H. Noon, C. Kittrell, J. Ma, R. H. Hauge, R. B. Weisman, R. E. Smalley, Science 297 593 (2002); Sergei M. Bachilo, Michael S. Strano Carter Kittrell, Robert H. Hauge, Richard E. Smalley, R. Bruce Weisman, Science 298 2361(2002); J. A. Misewich, R. Martel, Ph. Avouris, J. C. Tsang, S. Heinze, J. Tersoff, Science 300 783 (2003).